Paint particles sprayed from a paint gun or a like painting means are applied onto an object to be coated (hereinafter referred to as “workpiece”) within a paint booth. In this instance, uncoated paint particles float as a mist around the workpiece in an atmosphere of a paint booth. In order to secure a desired painting quality, a mist of paint particles should be promptly removed from the surroundings of the workpiece.
To this end, it has been a common practice that clean air supplied from an upper part of the paint booth flows downwards toward the workpiece, while at the same time, dirty air containing the paint mist is discharged from a bottom of the paint booth. From a standpoint of environmental protection, the paint mist must be removed from the dirty air before the air is vented to atmosphere.
To meet the requirement, the paint booth is generally provided with a paint mist collecting device, such as disclosed in Japanese Patent Application Laid-open Publication (JP-A) No. 2008-149248.
As shown here in FIG. 9, a wet booth circulation water treatment system disclosed in JP 2008-149248A includes a water tank 101 in which a circulation water is stored and purified. The purified circulation water is pumped up from the water tank 101 and supplied via a water supply line 104 into a paint booth 105 by means of a pump 103. The paint booth 105 has a bottom wall 106 formed into a V-shape. The supplied circulation water flows into a central outlet 107 formed in the V-shaped bottom wall 106 and falls down from the central outlet 107 during which time air containing the paint mist is entrained in the circulation water. In this instance, the air is washed with the circulation water and hence is purified.
Then, the circulation water and the air are separated from one another according to the difference in specific gravity, and the circulation water is allowed to further flow downward and eventually returns to the water tank 101. The air containing the paint mist is held in contact with the circulation water for a time period beginning from its entry to the central outlet 107 and ending at its separation from the circulation water. This contact time is not considered to be sufficiently long. In order to achieve a desired purification effect within such a limited contact time, an increased quantity of circulation water must be supplied. However, this requires a large-capacity pump, which will increase the running cost.
It is accordingly an object of the present invention to provide a paint mist collecting device which is capable of collecting a mist of paint particles floating within a paint booth without requiring a large quantity of cleaning liquid.
Another object of the present invention is to provide a paint booth equipped with such paint mist collecting device.